Drop-in, drop-out?
You'll be able to join friends or have them join you in online co-op games at any time with your persistent characters.

Four Mordecais?
You and your friends can play as any combination of character classes.

What if my friend is only level 5?
Players of any level will be able to join each other in games. We have not announced details about experience scaling for high-level characters fighting low-level enemies.

Ahhhh, thanks Aphex - sounds aces.

Indeed it does. I'm sure there will be a great pool of people to play with off these forums. Borderlands Thursdays anyone???????